Exception handling for controllers using ActionController::Live

Any exceptions that occured at the view or controller level for a
controller using ActionController::Live would cause the server to either
hang with an open socket indefinitely, or immediately crash (depending
on whether the server was launched with rails s or directly). Changed
the behavior of exceptions to act the same as streaming templates for
html requests, and allow for an on_error callback if needed.

1 files changed, 28 insertions, 0 deletions

diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index fb664a69dd..0a77352e57 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -56,6 +56,14 @@ module ActionController
         super
         @buf.push nil
       end
+
+      def on_error(&block)
+        @error_callback = block
+      end
+
+      def call_on_error
+        @error_callback.call
+      end
     end
 
     class Response < ActionDispatch::Response #:nodoc: all
@@ -121,6 +129,16 @@ module ActionController
 
         begin
           super(name)
+        rescue => e
+          begin
+            @_response.stream.write(ActionView::Base.streaming_completion_on_exception) if request.format == :html
+            @_response.stream.call_on_error
+          rescue => exceptionception
+            log_error(exceptionception)
+          ensure
+            log_error(e)
+            @_response.stream.close
+          end
         ensure
           @_response.commit!
         end
@@ -129,6 +147,16 @@ module ActionController
       @_response.await_commit
     end
 
+    def log_error(exception)
+      logger = ActionController::Base.logger
+      return unless logger
+
+      message = "\n#{exception.class} (#{exception.message}):\n"
+      message << exception.annoted_source_code.to_s if exception.respond_to?(:annoted_source_code)
+      message << "  " << exception.backtrace.join("\n  ")
+      logger.fatal("#{message}\n\n")
+    end
+
     def response_body=(body)
       super
       response.stream.close if response